Field of the Invention
The invention relates to signal processing of a transmission signal.
Description of the Background Art
Generally, a radar apparatus that is mounted on a host vehicle transmits plural types of transmission waves. Some among those waves are a horizontal transmission wave that is transmitted in a horizontal direction in which a transmission axis extends, relative to a road surface, and an upward transmission wave that is transmitted at a predetermined elevation angle relative to the transmission axis. Then, the radar apparatus derives information relating to a target (hereinafter referred to as “target information”) based on a reflection wave reflected by the target. The target information includes, for example, a reflection point on an object in a vertical direction relative to a road surface, in other words, a height of the object (target).
A vehicle controller obtains the target information output by the radar apparatus and determines whether the target is an upper object existing above the road, such as a billboard and a traffic sign, or the target is a front vehicle existing in front of the host vehicle, based on the height of the target. Then, the vehicle controller controls the vehicle based on a determined result of the target so as to ensure safety of the user.
The radar apparatus includes a connector that outputs the target information to the vehicle controller (hereinafter referred to as “radar connector”). Then, the radar connector is connected to a connector of the vehicle controller (hereinafter referred to as “vehicle connector”) via a cable of a predetermined length. The vehicle controller obtains the target information output by the radar apparatus.
However, in a case where a radar apparatus is mounted on a vehicle, depending on a type of the vehicle, the vehicle connector is located away from the radar connector so that it may be difficult to connect those connectors via the cable. For example, in a case where the radar connector is on one side of a housing of the radar apparatus (e.g. a right side) and the vehicle connector is provided to a portion close to another side of the housing of the radar apparatus (e.g. a left side), in other words, the vehicle connector is provided away from the one side, it may be difficult to connect both the connectors via the cable.
In this case, if the radar apparatus is mounted on the vehicle upside down instead of being mounted in a predetermined mounted state, the connectors can be connected to each other via the cable. However, in the case where the radar apparatus is mounted upside down, the transmission wave that should be transmitted upward is transmitted downward at a predetermined depression angle relative to the transmission axis. Therefore, the radar apparatus cannot derive the height of the target. As a result, the vehicle controller cannot correctly determine whether the target is the upper object or the front vehicle. Thus, the vehicle controller may not control the vehicle so as to ensure safety of the user.
In order that every radar apparatus mounted on the vehicle can transmit the transmission wave in a desired transmission direction (e.g. transmit transmission wave upward), plural types of the radar apparatuses need to be produced, for example, a radar apparatus including the radar connector on one side of the housing and a radar apparatus including the radar connector on another side. However, the plural types of the radar apparatus in different hardware configurations lead to an increase in designing burden and production costs.